Manufacture of electrodes for arc-lamps.



A. BLONDEL & G. DOBKEVITGH. MAN UPAGTURE 0F ELEGTRODESIOR ARG LAMPS.

APPLICATION FILED 00T.15, 1903.

v Patented May 9, 1911 FILLE )Fazer zone 0f' Zoram'are aided.

'UNITED STATES PATENT OFFICE.

ANDR BLONDEL ANI)y GATAN DoBxEvrroH, or PARIS, ramon, ASsrGNoRs, BY MESNE ,sflSsIeNMnNnrs` Toy GENERAL ELEoTRIccoMPANY, A CORPORATION or NEW YORK.

MANUFACTURE'OF ELECTRODES FOR ARC-LAMPS.

Patented May 9, 1911.

Application led October 15, 1903. Serial No.177,216.

To au whom it may concern:

Be it known that we, ANDR BLONDEL, engineer, of 41 Avenue de La Bourdonnais, Paris, a citizen of the Republic of FranceJ and GATAN DOBKEVITCH, engineer, of 81 Rue de lAssomption, Paris, France, a subject of the Emperorof Russia, have invented a new and useful Improvement in or Relate ing to the Manufacture of Electrodes for Arc-Lamps and the Like, which improvement is fully set forth in the following specification. y

This invention. relates to arc electrodes and consists in a new and u-seful type of arc electrodos composed of or comprising shaped masses of a composition comprising carbon, light-giving mineral substances and variou's borates having the property of regulating and cont-rolling the light; all as more fully hereinafter set forth andas claimed.

It has long been' known thatthe addition of various mineral substances, and particularly compounds of calciumL barium, strontium, magnesium, etc., to the carbon used for arc. electrodes is advantageous in producing certain lighting effects. Numerous tests by various experimenters have shown that the best results areafforded b calcium compounds, compounds of aluminum and magnesium having a smaller illuminating power, while strontium compoundsive the light too reddish a color. With fee le current intensities, calcium compounds also give a hue too yellow, or even too red. Moreover, carbons admixed with calcium lluorid or other calcium compounds, give a light which is very variable and is. disturbed by sudden luminous flashes, a fact which has prevented the use of such carbons for interior lighting. Various lluxes have heretofore been incorporated in these mineralized carbons in order to -give a liquid slag, such luxes containing various fusible compounds containing; silicates or comily fusible borates of the alkall meta-ls (sofdium, potassium, lithium, rubldium, .cae-

sium) in addition to the difticultly fusible 'borates of the alkaline earths, either singly pounds of boron, fluorin, sodium, potassium, etc., but these fluxes have not tended toimprove the light as regards whiteness and steadiness. Sodium and potassium and their compounds also make the slag'too fusible and they are besides too volatile, so that they leave the electrodes too quickly in the form of vapors -instead of remaining with the metallicssalts.

According to the present invention elec:

-phosphates are especially applicable.l The borates of the alkaline earths may include for the purposes of this invention the bof rates of barium, calcium, strontium, magneslum and the like. These act as the regulating borates in the electrode and hencewill herein be referred to as such. Y

The regulating borates are incorporatedl in the electrodes in relatively small amounts and constitute. about 10% of the other mineral substances present. Their proportion may, however, be as low as 5% or as high as 20% of the other mineral substances. A further addition of borates would weaken the illuminating power and render the slag too viscous and non-volatile. The borates mentioned are not yto be confused with the usual lluxes, the use of which is to be looked upon as detrimental. Their effect in addi-2 t-ion to the particular coloring of the light, consists rather in the improvement of the radiation of light and the regulation of the melting and vaporizat-ion of the metallic salts with which they are mixed and hence the' prevention of the disturbing flashing which occurs in the use of the ordinary mineralized electrodes, and which can not be avoided by the fluxes. .If the relatively infusible borates in combination with lluorspar are added to the electrodes, it is possible to operate the electrodes at higher temperature and thus lengthen their time of burning in the lamp as distinguished from such electrodes to which fluor-spar is added withoutthe'borates' nof the alkaline earths.

In order to further increase the yield of light, to insure an even consumption of thel electrode and to increase the conductivity of the arc, it is'advisable to add more reador fmixed with one another, so that their total mass amounts to y20% of the l1ght 4 yielding calcium compounds. By the addition of the borates of the alkali metals the color of the light is at the same time 1nfluenced Without affecting the advantageous working of the borates of the alkaline earths and without resulting in anI unsteady lighiJ or too volatile slag which occur in the otherwise known use of the borates of the alkali metals.

Of the borates of the alkaline earths in connection with the calcium borate, the boi'ate of barium which tends to whiten the color of the arc flame, is especially suitable. If sodium borate is employed with barium borate, the light becomes yellowish. If potassium borate takes t-he place of a part of the barium borate, it becomes rich yellow and dull; if magnesium borat-e is, used in placeof a part of the barium borate, it becomes greeneror when strontium borate is used it becomes morerosy. y

- As an example of a suitable composition for the carbon, may be mentioned 50 to 70%r carbon combined with 50 tok 30% of a mixture of' uor-spar and the borates of the alkaline earths in which mixture the borates form about 10% of the fluor-spar. One of the borates alone or several mixed together may be employed according to the color of light which is desired. If borates of the alkali metals are used in addition to the Vborates of the alkaline earths, a good mixture is obtained by taking for example 1. kg. fluor-spar, 0.1, kg. of one or several of the borates of the alkaline earths and 0.1 kg. of one of the borates of the alkali metals or several o-f these latter mixed together. This mixture can be Worked in the ordinary manner and in the usual relations with carbon. An especially good result is obtained, however, by introducing the mineral substancees into the inner part of the electrode and surrounding it with a mantle composed of essentially pure carbon, as described in United States Letters Patent No. 714,277

granted to Andr Blondel, on November 25th, 1902.

In making the new composition, the regulating borates are preferably mixed with the light-giving mineral substances before incorporating the carbon, such mixture being performed either wet or-dry. The pulverized substances may be stirred together with water, or they may befused together and the melt powdered. The carbon paste is made' in the ordinary manner. After mixing it with the mineral substances, themass is forced out through a die plate or the like in In the accompanying illustrations, we

have shown, more or less diagrammatically, electrodes made according to the present invention.

In this showing: Figure 1 illustrates a homogeneous composite carbon made of our new composition; Fig. 2 is a cored electrode; Fig. 3 an electrode having two zones or layers, of which the inner is a body of our composite carbon and the outer a body of carbon alone; and Fig. 4 an electrode having a cored composite carbon with an outer layer of carbon. A

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is,

1. An electrode for electric lights containing an intimate mixture of mineral sub-` stances consisting of 95 to 80% of a light giving mineral substance and 5 to 20% of borates of alkaline earths adapted to remain in and be consumed with the other constituents of the electrode and thereby regulate giving mineral substance and 5 to 10% ot" borates of the alkaline earths and 5 to 10% of boratesof alkaline metals adapted to remain in and be consumed with the other constituents of the electrode and thereby regulate the light.

3. An electrode for electric lights containing a light giving mineral substance and bor'ate of barium.

4. .An electrode for electric lights containing a light giving mineral substance, a borate of an alkali metal and borate of barium.

In ,testimony whereof we have signed this specification in the ing witnesses.

' ANDR BLONDEL;

GATAN DOBKEVITCH. Witnesses:

AUGUSTUS INGRAin PAUL MATHIEU.

presence of two subscrib- 

